The invention relates to a device for scanning a layer of a medium in accordance with a track pattern formed by a longitudinal path of substantially parallel tracks which have a substantially constant track pitch and have a track direction transverse to the longitudinal direction of the path, the device comprising an optical system for focusing a radiation beam at the layer, while the radiation beam causes a scanning spot to develop on the layer, scanning means for causing the scanning spot to be displaced with a specific repetition rate over the layer along a scanning path that has a specific scanning direction, driver means for causing the medium to be displaced relative to the scanning means with a certain velocity in a direction transverse to the scanning direction, in which device, when operative, vibrations occur which cause the scanning spot to be displaced over the layer in a direction transverse to the scanning direction, which displacements of the scanning spot have an amplitude that exceeds the track pitch.
Such a device is known from U.S. Pat. No. 4,901,297. In the known device a path of parallel tracks on a tape-like record carrier is realised, which record carrier is displaced relative to an optical scanner. The optical scanner scans the record carrier repeatedly in a direction transverse to the direction of displacement of the tape-like record carrier.
For the tracking during recording the known device comprises a fine adjustment which corrects the position of the scanning spot in a direction transverse to the direction of the track in response to a detected tracking error, so that the recording scanning spot is maintained substantially in the middle of the track. During this operation the tracking error is derived with respect to a predetermined track pattern. The disadvantage of prior-art device is that a recording, during which the distance between the middles of two successive tracks (also denoted track pitch) remains substantially constant over the whole length of two successive tracks, is only possible if the record carrier used already has a prearranged track pattern.